Messages in this thread | | | From | Ard Biesheuvel <> | Date | Fri, 13 Nov 2020 08:43:14 +0100 | Subject | Re: [PATCH V3] arm64/mm: Validate hotplug range before creating linear mapping |
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On Fri, 13 Nov 2020 at 08:31, Anshuman Khandual <anshuman.khandual@arm.com> wrote: > > During memory hotplug process, the linear mapping should not be created for > a given memory range if that would fall outside the maximum allowed linear > range. Else it might cause memory corruption in the kernel virtual space. > > Maximum linear mapping region is [PAGE_OFFSET..(PAGE_END -1)] accommodating > both its ends but excluding PAGE_END. Max physical range that can be mapped > inside this linear mapping range, must also be derived from its end points. > > This ensures that arch_add_memory() validates memory hot add range for its > potential linear mapping requirements, before creating it with > __create_pgd_mapping(). > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: Steven Price <steven.price@arm.com> > Cc: Robin Murphy <robin.murphy@arm.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Fixes: 4ab215061554 ("arm64: Add memory hotplug support") > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > This applies on 5.10-rc3 > > Changes in V3: > > - Dropped comment paragraphs from code and commit message per Ard > - Dropped parenthesis brackets in the comparison per Ard > > Changes in V2: (https://lore.kernel.org/linux-arm-kernel/1605236574-14636-1-git-send-email-anshuman.khandual@arm.com/) > > - Replaced (start + size) with (start + size - 1) in the comparison per Ard > - Dropped parenthesis brackets in the comparison per Ard > > Changes in V1: (https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/) > > arch/arm64/mm/mmu.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 1c0f3e02f731..ca692a815731 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1444,11 +1444,28 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) > free_empty_tables(start, end, PAGE_OFFSET, PAGE_END); > } > > +static bool inside_linear_region(u64 start, u64 size) > +{ > + /* > + * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] > + * accommodating both its ends but excluding PAGE_END. Max physical > + * range which can be mapped inside this linear mapping range, must > + * also be derived from its end points. > + */ > + return start >= __pa(_PAGE_OFFSET(vabits_actual)) && > + (start + size - 1) <= __pa(PAGE_END - 1); > +} > + > int arch_add_memory(int nid, u64 start, u64 size, > struct mhp_params *params) > { > int ret, flags = 0; > > + if (!inside_linear_region(start, size)) { > + pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size); > + return -EINVAL; > + } > + > if (rodata_full || debug_pagealloc_enabled()) > flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; >
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
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